62 lines
4.5 KiB
Markdown
62 lines
4.5 KiB
Markdown
A data structure for optimistic concurrency control on ranges of bitwise-lexicographically-ordered keys.
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Intended as an alternative to FoundationDB's skip list.
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Hardware for all benchmarks is an AMD Ryzen 9 7900 with (2x32GB) 5600MT/s CL28-34-34-89 1.35V RAM.
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Compiler is `Ubuntu clang version 20.0.0 (++20241029082144+7544d3af0e28-1~exp1~20241029082307.506)`.
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# Microbenchmark
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## Skip list
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| ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark
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|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
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| 159.65 | 6,263,576.52 | 1.6% | 2,972.36 | 820.37 | 3.623 | 504.59 | 0.0% | 0.01 | `point reads`
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| 156.32 | 6,397,320.65 | 0.7% | 2,913.62 | 806.87 | 3.611 | 490.19 | 0.0% | 0.01 | `prefix reads`
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| 229.18 | 4,363,293.65 | 1.2% | 3,541.05 | 1,219.75 | 2.903 | 629.33 | 0.0% | 0.01 | `range reads`
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| 363.37 | 2,752,026.30 | 0.3% | 5,273.63 | 1,951.54 | 2.702 | 851.66 | 1.7% | 0.01 | `point writes`
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| 364.99 | 2,739,787.02 | 0.3% | 5,250.92 | 1,958.54 | 2.681 | 839.24 | 1.7% | 0.01 | `prefix writes`
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| 242.26 | 4,127,796.58 | 2.9% | 3,117.33 | 1,304.41 | 2.390 | 541.07 | 2.8% | 0.02 | `range writes`
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| 562.48 | 1,777,855.27 | 0.8% | 7,305.21 | 3,034.34 | 2.408 | 1,329.30 | 1.3% | 0.01 | `monotonic increasing point writes`
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| 122,688.57 | 8,150.72 | 0.7% | 798,766.00 | 666,842.00 | 1.198 | 144,584.50 | 0.1% | 0.01 | `worst case for radix tree`
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| 41.71 | 23,976,459.34 | 1.7% | 885.00 | 219.17 | 4.038 | 132.00 | 0.0% | 0.01 | `create and destroy`
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## Radix tree (this implementation)
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| ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark
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|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
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| 12.63 | 79,186,868.18 | 1.4% | 241.61 | 64.76 | 3.731 | 31.64 | 0.8% | 0.01 | `point reads`
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| 14.48 | 69,078,073.40 | 0.3% | 292.42 | 74.69 | 3.915 | 41.49 | 0.5% | 0.01 | `prefix reads`
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| 34.37 | 29,094,694.11 | 0.2% | 759.53 | 179.77 | 4.225 | 100.38 | 0.2% | 0.01 | `range reads`
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| 19.34 | 51,713,896.36 | 0.7% | 369.70 | 101.81 | 3.631 | 47.88 | 0.6% | 0.01 | `point writes`
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| 39.16 | 25,538,968.61 | 0.2% | 653.16 | 206.77 | 3.159 | 89.62 | 0.8% | 0.01 | `prefix writes`
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| 40.58 | 24,642,681.12 | 4.7% | 718.44 | 216.44 | 3.319 | 99.28 | 0.6% | 0.01 | `range writes`
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| 78.77 | 12,694,520.69 | 3.8% | 1,395.55 | 421.73 | 3.309 | 249.81 | 0.1% | 0.01 | `monotonic increasing point writes`
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| 287,760.50 | 3,475.11 | 0.5% | 3,929,266.50 | 1,550,225.50 | 2.535 | 639,064.00 | 0.0% | 0.01 | `worst case for radix tree`
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| 104.76 | 9,545,250.65 | 3.1% | 2,000.00 | 552.82 | 3.618 | 342.00 | 0.0% | 0.01 | `create and destroy`
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# "Real data" test
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Point queries only, best of three runs. Gc ratio is the ratio of time spent doing garbage collection to time spent adding writes or doing garbage collection. Lower is better.
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## skip list
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```
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Check: 4.39702 seconds, 370.83 MB/s, Add: 4.50025 seconds, 124.583 MB/s, Gc ratio: 29.1333%, Peak idle memory: 5.51852e+06
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```
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## radix tree
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```
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Check: 0.987757 seconds, 1650.76 MB/s, Add: 1.24815 seconds, 449.186 MB/s, Gc ratio: 41.4675%, Peak idle memory: 2.02872e+06
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```
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## hash table
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(The hash table implementation doesn't work on range queries, and its purpose is to provide an idea of how fast point queries can be)
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```
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Check: 0.84256 seconds, 1935.23 MB/s, Add: 0.697204 seconds, 804.146 MB/s, Gc ratio: 35.4091%
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```
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